Figures 6.5 and 6.6 allow you to identify certain regions and landmarks in the fetal skull, which have particular importance for obstetric care because they may form the so-called presenting part of the fetus — that is, the part leading the way down the birth canal.
- The vertex is the area midway between the anterior fontanel, the two parietal bones and the posterior fontanel. A vertex presentation occurs when this part of the fetal skull is leading the way. This is the normal and the safest presentation for a vaginal delivery.
- The brow is the area of skull which extends from the anterior fontanel to the upper border of the eye. A brow presentation is a significant risk for the mother and the baby.
- The face extends from the upper ridge of the eye to the nose and chin (lower jaw). A face presentation is also a significant risk for the mother and baby.
- The occiput is the area between the base of the skull and the posterior fontanel. It is unusual and very risky for the occiput to be the presenting part.
When you study the next Module on Labour and Delivery Care, you will learn about other presentations, including 'breech' (the baby is head-up and its feet or bottom is the presenting part), and 'shoulder' first.
Now that you know all the major anatomical features of the female reproductive system, the female pelvis and the fetal skull, we move on in Study Session 7 to consider the major physiological changes that take place in a woman's body during pregnancy.